Role of a specific choline pool in sphingomyelin synthesis in rat heart

Abstract

Sphingomyelin synthesis was studied in slices of rat heart by using [Me-14C]choline, [1,2-14C]ethanolamine, S-adenosyl-L-[14C]methionine and [32P]Pi as as precursors. In the presence of both [Me-14C]choline and [32P]Pi the ratio of the specific radioactivities of 14C and 32P in phosphatidylcholine was greater than in sphingomyelin at all the times studied. This suggested that synthesis of phosphatidylcholine and sphingomyelin de novo did not involve the utilization of a common pool of cytidine diphosphate choline. In addition, studies with [1,2-14C]ethanolamine and S-adenosyl-L-[14C]methionine indicated that a quantitatively significant pool of choline, derived from these precursors, was selectively utilized for sphingomyelin formation. This pool was not represented by phosphatidylcholine formed by methylation of phosphatidylethanolamine or by other pathways.

Tight connection between choline transport and phosphatidylcholine synthesis in MDCK cells

“…In accordance with this hypothesis, the existence of intracellular pools of choline in MDCK cells was demonstrated by the fact that choline entering from the basolateral side was poorly mixed with choline entering from the apical side : choline efflux from cells loaded from the basolateral side occurred from the same compartment, whereas more than one-third of the choline loaded from the apical side was released into the basolateral bath. It is noteworthy that the existence of different pools of intracellular choline was previously reported in rat liver [31] and heart [32]. It has also been suggested that, in BHK cells, the phosphorylation of choline occurs when it is transported into the cells, with the cellular choline pool not being involved in PC synthesis [22].…”

Improved Synthesis of Cytidine Diphosphate Choline (CDP-Choline) Via Selective Phosphorylation

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Cytidine diphosphate choline (CDP-choline 1) is a nucleotide coenzyme and serves as a choline donor in the biosynthesis of lipids, 1 lecithins, 2 and sphingomyelin. 3 It is a clinical drug for the treatment of several illnesses involving disturbance of the central nervous system, in particular, for regaining a patient's consciousness and for treatment of neuropsychic symptoms occurring during skull traumas and brain surgery. 4 Among various methods for the synthesis of CDP-choline in the literature, the current preferred method is via the condensation of cytidine-5'-phosphomorpholide (2) with choline phosphate chloride (3) under mild reaction conditions.

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